Life History

Food

The main food taken by the Guianan Cock-of-the-rock is fruit. They occasionally also take insects or small vertebrates. Up to 65 species of fruit are reported in the diet, primarily from canopy trees or lianas (Enard et al. 1989). Three quarters (75%) of the fruit eaten by the Guianan Cock-of-the-rock at one study site was either black or red colored fruit (Enard et al. 1989).

Behavior

Although the Guianan Cock-of-the-rock is a large, stocky bird, they fly agilely through the forest (Snow 1982). Forage for fruit with sallies (Snow 1982).

Regurgitates large seeds; consequently, quantities of seeds often accumulate on the ground below and near the nest.

Territoriality

Males defend individual display courts on the lek.

Sexual Behavior

Mating system and sex ratios

Guianan Cock-of-the-rock is polygynous, with a single male breeding with multiple females.

Pair bond

The Guianan Cock-of-the-rock maintains no long term pair bonds. The female lays the eggs and rears the young with no assistance from the male.

Courtship display

The Guianan Cock-of-the-rock males display at a lek (communal display area). At the lek, each male maintains a separate "court", cleared of vegetation, on the forest floor. Males spend much of their time, however, perched above the court, generally at about 1.5 to 2 m above the court (Trail 1987). When a female visits the lek, males descend to their courts, ruffle their plumage, and crouch motionless. (Gilliard 1962, Sick 1984.) The small curled filament tips of the secondaries on the wings are moved up into a fan like shape when faced against a small breeze (Gilliard 1962, Sick 1984.)

If a female descends to a male's courts, she then may tap him on the back or shoulder. This is followed by copulation. A female may return later to copulate again, either with the same male or with another (Trail 1989). About two-thirds (67%) of the males at one lek failed to reproduce, while the most successful male performed an average of 30% of the total number of annual matings (Trail 1969).

Social and interspecific behavior

The Guianan Cock-of-the-rock is a solitary, other than at the lek.

Predation

The primary predators of the Guianan Cock-of-the-rock are Harpy Eagles (Harpia harpyja), Black-and-white Hawk-Eagles (Spizaetus melanoleucus), Black Hawk-Eagles (Spizaetus tyrannus), and Slaty-backed Forest-Falcons (Micrastur mirandollei) (Trail 1987). Other predators that have a lesser impact are two species of owls, Crested (Lophostrix cristata) and Spectacled (Pulsatrix perspicillata) owls (Trail 1987). Other predators include felids, such as jaguar (Panthera onca), puma (Puma concolor), and ocelot (Leopardus pardalis); and snakes, such as bird snake (Pseustes poecilonotus), the tree boas (Corallus caninus and Corallus enydris), the boa constrictor (Boa constrictor), the tiger rat snake (Spilotes pullatus), and the fer-de-lance (Bothrops atrox) (Trail 1967). At one site, three males were killed within the same lek by the same snake in the course of a year (Trail 1987).

Response to predation

The Guianan Cock-of-the-rock has been shown to have less predation in larger lek groups due to the alertness of having several individuals on the lookout for predators. Within a large group, more spooks (“false” alarm) are likely to happen due to the amount of birds looking for predators and alarming the large lek group (Trail 1987). In the lek, the response to predators is the vocalization projected at the stimulus (Trail 1987). Usually after such a call, the majority of the birds at the lek retreat ca 20-30 m up into trees. Predation by snakes, however, did not seem to cause an alarm call or a spook. Most of the time when a snake was passing through the lek, none of the birds took notice; the birds did not even give an alarm call when a male was attacked on his court by a boa (Trail 1987).

Reproduction

Nests are located on rocky outcrops or near rocky streams in shady forests. They are built around December and January when the breeding season begins. The nest is made of mud and sticks and placed on the wall of an outcrop (Sick 1984). The female builds the nest by herself.

The clutch is two. Eggs are pale buffy brown to very pale buff, marked with pale lilac-gray, especially around the larger end (Snow 1982). Incubation is 27-28 days (Snow 1982). Only the female incubates. Chicks primarily are provisioned with fruit, but the occasional insect or small vertebrate is also feed to the young (Enard et al. 1989).